McBrearty, whose wrongful arrest on suspicion of murder led to the establishment of the Morris tribunal, was removed from a lecture hall minutes before McDowell addressed a student society.

However, the university has claimed that the Donegal man was asked to leave the event only because he was not a student.

McDowell addressed a joint Young PDs and Law Society event in Belfield last week. McBrearty, whose daughter is a student in the university, requested permission from the student organisers to attend the event. However, while this permission was granted, he was requested to leave the lecture hall shortly after arriving.

The head of security on the night has denied claims that McBrearty was removed due to his dispute with the minister. According to Richard Butler, the decision was made to make the event open to students only. High-profile events in the university have been made student-only due to disturbances at an immigration debate attended by Justin Barrett a number of years ago, he said, adding that up to 12 non-students, including McBrearty and his wife Rosalind McBrearty, were asked to leave the lecture hall prior to McDowell's arrival.

Posters for the event clearly stated that attendees must hold valid student cards, said Butler.

A spokeswoman for Michael McDowell said that the decision to remove McBrearty was made by the security team on the night.

The Minister for Justice had met with McBrearty on several occasions over recent years and, while these meetings had sometimes been heated, there would be no reason for the minister to object to the Donegal man's presence.

Frank McBrearty Snr refused to comment on the matter.